This paper discusses an optimisation of methyl orange photodegradation using TiO2-zeolite photocatalyst and H2O2 (with condition of pH 2, 10 ppm, UV light). A 15 mmol TiO2 in 1 gram activated zeolite was used. The influence of H2O2 concentration (4, 8, 12, 16%) and irradiation time (20, 30 40, 50, 60 minutes) was also investigated, as well as initial methyl orange concentration (10, 20, 30 ppm) toward reaction rate constant. As the H2O2 concentration increase, the photodegradation percentage is also increased until it reaches optimum condition (H2O212% for 10 ppm MO solution). Identical effect also showed by the irradiation time in which an optimum point reached at 60 minutes (for 10 ppm MO solution) and 50 minutes (for 20 and 30 ppm MO solutions). Moreover, the higher initial MO concentration used, the lower reaction rate constant obtained. The highest rate constant was shown by MO solution of 10 ppm. The reuse of TiO2-Zeolite photocatalyst remains effective and efficient in photodegradation of methyl orange in solution for up to 4 times.

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Chitosan-silica prepared by sol-gel method was used for adsorption of M(II) (M = Mn 2+ , Cu 2+ , Zn 2+ ) in solution at room temperature. The prepared chitosan-silica was characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). Effect of pH of the metal solution and adsorption contact time toward the adsorption capacity were investigated. The correlation between M(II) concentrations and the adsorption capacity, which was determined at optimum pH and optimum adsorption contact time, is also discussed. FTIR and SEM results are identical to that of chitosan-silica reported previously. Chitosan-silica performs the highest adsorption capacity for Cu 2+ , Mn 2+ , and Zn 2+ , successively. The optimum pH for Mn 2+ , Cu 2+ and Zn 2+ adsorptions were obtained at pH 5. It is suggested that due to the combination of ionic size and HSAB concept, Cu 2+ gives the highest adsorption capacity than that of Mn 2+ and Zn 2+ . The optimum contact time for Mn 2+ and Cu 2+ adsorption was obtained at 75 minutes with adsorption capacities of 6.56 ± 0.04 mg/g and 15.46 ± 0.02 mg/g, respectively, whereas Zn 2+ adsorption was obtained at 60 minutes with an adsorption capacity of 5.01 ± 0.12 mg/g.

Ligand selectivity of tartrate vs nicotinamide in a water-methanol system has been observed in the crystallization of Mn(II) and Cd(II) complexes. These complexes were crystallized at room temperature by a layered solution technique using a water-methanol mixture solvent in a M(II):tartrate:nicotinamide (M = Mn, Cd) molar ratio of 1:1:2. Complexes of M(II)-nicotinamide and M(II)-tartrate were also prepared for data comparison. Analysis of the crystals by infrared spectroscopy, powder-X-ray diffraction and qualitative anion test showed that in a presence of both tartrate and nicotinamide, the Mn(II) forms neutral Mn(II)-tartrate hydrate complex, whereas the Cd(II) forms ionic Cd(II)-nicotinamide chloride complex. In the case of Mn(II) complex, tartrate tend to coordinate as ligand than the nicotinamide, although molar ratio of nicotinamide was doubled than that of tartrate ligand. In contrast, the neutral nicotinamide ligand is more predominant to coordinate in the Cd(II) complex than the anionic tartrate. The tartrate-nicotinamide ligand selectivity in the crystallization of Mn(II) and Cd(II) complexes is likely due to the use of tartrate salt as precursor and the choice of solvent mixture. In addition, powder-XRD analysis confirms that there was no indication of M(II)-tartrate and M(II)-nicotinamide that co-crystallized together at the same time by both metal ions.